/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2002,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.util;

import com.sun.org.apache.xerces.internal.xni.grammars.Grammar;
import com.sun.org.apache.xerces.internal.xni.grammars.XMLGrammarDescription;
import com.sun.org.apache.xerces.internal.xni.grammars.XMLGrammarPool;

/**
 * Stores grammars in a pool associated to a specific key. This grammar pool
 * implementation stores two types of grammars: those keyed by the root element
 * name, and those keyed by the grammar's target namespace.
 *
 * This is the default implementation of the GrammarPool interface.
 * As we move forward, this will become more function-rich and robust.
 *
 * @author Jeffrey Rodriguez, IBM
 * @author Andy Clark, IBM
 * @author Neil Graham, IBM
 * @author Pavani Mukthipudi, Sun Microsystems
 * @author Neeraj Bajaj, SUN Microsystems
 */
public class XMLGrammarPoolImpl implements XMLGrammarPool {

  //
  // Constants
  //

  /**
   * Default size.
   */
  protected static final int TABLE_SIZE = 11;

  //
  // Data
  //

  /**
   * Grammars.
   */
  protected Entry[] fGrammars = null;

  // whether this pool is locked
  protected boolean fPoolIsLocked;

  // the number of grammars in the pool
  protected int fGrammarCount = 0;

  private static final boolean DEBUG = false;

  //
  // Constructors
  //

  /**
   * Constructs a grammar pool with a default number of buckets.
   */
  public XMLGrammarPoolImpl() {
    fGrammars = new Entry[TABLE_SIZE];
    fPoolIsLocked = false;
  } // <init>()

  /**
   * Constructs a grammar pool with a specified number of buckets.
   */
  public XMLGrammarPoolImpl(int initialCapacity) {
    fGrammars = new Entry[initialCapacity];
    fPoolIsLocked = false;
  }

  //
  // XMLGrammarPool methods
  //

  /* <p> Retrieve the initial known set of grammars. This method is
   * called by a validator before the validation starts. The application
   * can provide an initial set of grammars available to the current
   * validation attempt. </p>
   *
   * @param grammarType The type of the grammar, from the
   *                    <code>com.sun.org.apache.xerces.internal.xni.grammars.XMLGrammarDescription</code>
   *                    interface.
   * @return            The set of grammars the validator may put in its "bucket"
   */
  public Grammar[] retrieveInitialGrammarSet(String grammarType) {
    synchronized (fGrammars) {
      int grammarSize = fGrammars.length;
      Grammar[] tempGrammars = new Grammar[fGrammarCount];
      int pos = 0;
      for (int i = 0; i < grammarSize; i++) {
        for (Entry e = fGrammars[i]; e != null; e = e.next) {
          if (e.desc.getGrammarType().equals(grammarType)) {
            tempGrammars[pos++] = e.grammar;
          }
        }
      }
      Grammar[] toReturn = new Grammar[pos];
      System.arraycopy(tempGrammars, 0, toReturn, 0, pos);
      return toReturn;
    }
  } // retrieveInitialGrammarSet (String): Grammar[]

  /* <p> Return the final set of grammars that the validator ended up
   * with. This method is called after the validation finishes. The
   * application may then choose to cache some of the returned grammars.</p>
   * <p>In this implementation, we make our choice based on whether this object
   * is "locked"--that is, whether the application has instructed
   * us not to accept any new grammars.</p>
   *
   * @param grammarType The type of the grammars being returned;
   * @param grammars    An array containing the set of grammars being
   *                    returned; order is not significant.
   */
  public void cacheGrammars(String grammarType, Grammar[] grammars) {
    if (!fPoolIsLocked) {
      for (int i = 0; i < grammars.length; i++) {
        if (DEBUG) {
          System.out.println("CACHED GRAMMAR " + (i + 1));
          Grammar temp = grammars[i];
          //print(temp.getGrammarDescription());
        }
        putGrammar(grammars[i]);
      }
    }
  } // cacheGrammars(String, Grammar[]);

  /* <p> This method requests that the application retrieve a grammar
   * corresponding to the given GrammarIdentifier from its cache.
   * If it cannot do so it must return null; the parser will then
   * call the EntityResolver. </p>
   * <strong>An application must not call its EntityResolver itself
   * from this method; this may result in infinite recursions.</strong>
   *
   * This implementation chooses to use the root element name to identify a DTD grammar
   * and the target namespace to identify a Schema grammar.
   *
   * @param desc The description of the Grammar being requested.
   * @return     The Grammar corresponding to this description or null if
   *             no such Grammar is known.
   */
  public Grammar retrieveGrammar(XMLGrammarDescription desc) {
    if (DEBUG) {
      System.out.println("RETRIEVING GRAMMAR FROM THE APPLICATION WITH FOLLOWING DESCRIPTION :");
      //print(desc);
    }
    return getGrammar(desc);
  } // retrieveGrammar(XMLGrammarDescription):  Grammar

  //
  // Public methods
  //

  /**
   * Puts the specified grammar into the grammar pool and associates it to
   * its root element name or its target namespace.
   *
   * @param grammar The Grammar.
   */
  public void putGrammar(Grammar grammar) {
    if (!fPoolIsLocked) {
      synchronized (fGrammars) {
        XMLGrammarDescription desc = grammar.getGrammarDescription();
        int hash = hashCode(desc);
        int index = (hash & 0x7FFFFFFF) % fGrammars.length;
        for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
          if (entry.hash == hash && equals(entry.desc, desc)) {
            entry.grammar = grammar;
            return;
          }
        }
        // create a new entry
        Entry entry = new Entry(hash, desc, grammar, fGrammars[index]);
        fGrammars[index] = entry;
        fGrammarCount++;
      }
    }
  } // putGrammar(Grammar)

  /**
   * Returns the grammar associated to the specified grammar description.
   * Currently, the root element name is used as the key for DTD grammars
   * and the target namespace  is used as the key for Schema grammars.
   *
   * @param desc The Grammar Description.
   */
  public Grammar getGrammar(XMLGrammarDescription desc) {
    synchronized (fGrammars) {
      int hash = hashCode(desc);
      int index = (hash & 0x7FFFFFFF) % fGrammars.length;
      for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
        if ((entry.hash == hash) && equals(entry.desc, desc)) {
          return entry.grammar;
        }
      }
      return null;
    }
  } // getGrammar(XMLGrammarDescription):Grammar

  /**
   * Removes the grammar associated to the specified grammar description from the
   * grammar pool and returns the removed grammar. Currently, the root element name
   * is used as the key for DTD grammars and the target namespace  is used
   * as the key for Schema grammars.
   *
   * @param desc The Grammar Description.
   * @return The removed grammar.
   */
  public Grammar removeGrammar(XMLGrammarDescription desc) {
    synchronized (fGrammars) {
      int hash = hashCode(desc);
      int index = (hash & 0x7FFFFFFF) % fGrammars.length;
      for (Entry entry = fGrammars[index], prev = null; entry != null;
          prev = entry, entry = entry.next) {
        if ((entry.hash == hash) && equals(entry.desc, desc)) {
          if (prev != null) {
            prev.next = entry.next;
          } else {
            fGrammars[index] = entry.next;
          }
          Grammar tempGrammar = entry.grammar;
          entry.grammar = null;
          fGrammarCount--;
          return tempGrammar;
        }
      }
      return null;
    }
  } // removeGrammar(XMLGrammarDescription):Grammar

  /**
   * Returns true if the grammar pool contains a grammar associated
   * to the specified grammar description. Currently, the root element name
   * is used as the key for DTD grammars and the target namespace  is used
   * as the key for Schema grammars.
   *
   * @param desc The Grammar Description.
   */
  public boolean containsGrammar(XMLGrammarDescription desc) {
    synchronized (fGrammars) {
      int hash = hashCode(desc);
      int index = (hash & 0x7FFFFFFF) % fGrammars.length;
      for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
        if ((entry.hash == hash) && equals(entry.desc, desc)) {
          return true;
        }
      }
      return false;
    }
  } // containsGrammar(XMLGrammarDescription):boolean

  /* <p> Sets this grammar pool to a "locked" state--i.e.,
   * no new grammars will be added until it is "unlocked".
   */
  public void lockPool() {
    fPoolIsLocked = true;
  } // lockPool()

  /* <p> Sets this grammar pool to an "unlocked" state--i.e.,
   * new grammars will be added when putGrammar or cacheGrammars
   * are called.
   */
  public void unlockPool() {
    fPoolIsLocked = false;
  } // unlockPool()

  /*
   * <p>This method clears the pool-i.e., removes references
   * to all the grammars in it.</p>
   */
  public void clear() {
    for (int i = 0; i < fGrammars.length; i++) {
      if (fGrammars[i] != null) {
        fGrammars[i].clear();
        fGrammars[i] = null;
      }
    }
    fGrammarCount = 0;
  } // clear()

  /**
   * This method checks whether two grammars are the same. Currently, we compare
   * the root element names for DTD grammars and the target namespaces for Schema grammars.
   * The application can override this behaviour and add its own logic.
   *
   * @param desc1 The grammar description
   * @param desc2 The grammar description of the grammar to be compared to
   * @return True if the grammars are equal, otherwise false
   */
  public boolean equals(XMLGrammarDescription desc1, XMLGrammarDescription desc2) {
    return desc1.equals(desc2);
  }

  /**
   * Returns the hash code value for the given grammar description.
   *
   * @param desc The grammar description
   * @return The hash code value
   */
  public int hashCode(XMLGrammarDescription desc) {
    return desc.hashCode();
  }

  /**
   * This class is a grammar pool entry. Each entry acts as a node
   * in a linked list.
   */
  protected static final class Entry {

    public int hash;
    public XMLGrammarDescription desc;
    public Grammar grammar;
    public Entry next;

    protected Entry(int hash, XMLGrammarDescription desc, Grammar grammar, Entry next) {
      this.hash = hash;
      this.desc = desc;
      this.grammar = grammar;
      this.next = next;
    }

    // clear this entry; useful to promote garbage collection
    // since reduces reference count of objects to be destroyed
    protected void clear() {
      desc = null;
      grammar = null;
      if (next != null) {
        next.clear();
        next = null;
      }
    } // clear()
  } // class Entry

    /* For DTD build we can't import here XSDDescription. Thus, this method is commented out.. */
    /* public void print(XMLGrammarDescription description){
        if(description.getGrammarType().equals(XMLGrammarDescription.XML_DTD)){

        }
        else if(description.getGrammarType().equals(XMLGrammarDescription.XML_SCHEMA)){
            XSDDescription schema = (XSDDescription)description ;
            System.out.println("Context = " + schema.getContextType());
            System.out.println("TargetNamespace = " + schema.getTargetNamespace());
            String [] temp = schema.getLocationHints();

            for (int i = 0 ; (temp != null && i < temp.length) ; i++){
                System.out.println("LocationHint " + i + " = "+ temp[i]);
            }

            System.out.println("Triggering Component = " + schema.getTriggeringComponent());
            System.out.println("EnclosingElementName =" + schema.getEnclosingElementName());

        }

    }//print
    */

} // class XMLGrammarPoolImpl
